Make two chalk lines that cross in the very center of the floor and start from there. Open a couple of boxes of each color and mix the tiles, as the color can vary from box to box. It may not be noticeable since no two tiles of the same color are going to be adjacent. Also, make sure the floor is PERFECTLY clean. One grain of sand will show up as a bump in the tile in a couple of years. I put mine shiny side up and they've looked good for 10 years.
Wait ...
Here is a pretty good step by step:
How to Lay a Vinyl Tile Floor | Step-by-Step | Floors | This Old House - 5